Lift



l. V. K. HOTT ETAL LIFT Filed April l0, 1965 June 1, 1965 THE/f ATTOH/ve v5 JIE. 1

W s u i, o .n m M United States Patent() This invention .relates to a lift structure and more particularly to a bearing structure used in guiding the m-ovement of an automotive lift piston relative to a lift cylinder, although not necessarily so limited.

An object of this invention is to provide an improved bearing structure for an automotive lift.

A conventional automotive lift employs a superstructure whi-ch is attached to the top of a` piston or rain slidable vertically within a cylinder mounted in a pit. The slidable movement of the piston relative to the cylinder is normally guided by a pair of spaced bearing rings affixed to the cylinder. in operation, either compressed air or uid under pressure forces the piston upwardly within the cylinder until stop members at the base of the piston engage the lower bearing rings or o-ther cooperating stop elements Within the cylinder.

There are two basic types of conventional litt bearing structures. One type employs a lower bearing ring welded or otherwise permanently attached to the cylinder. With conventional permanently attached lower bearings, it is impossible to remove the piston from the cylinder without either destroying the bearing structure or removing the cylinder from the pit within the floor or ground in which it is placed. The other type has a removable lower bearing which is in threaded engagement with the internal surface of the cylinder or is otherwise removably attached thereto. T he latter type of bearing structure is usually preferred since the piston may more readily be re` moved from the cylinder for repair.

A more speciiic object of thisV invention is to provide an improved removable lower bearing for use in a lift structure.

A further object of this invention is the provision of an improved upper bearing structure having advantages which will be discussed below.

Other objects and advantages reside in the construction of parts, the combination thereof, the method of manufacture and the mode of operation, as will become more apparent from the following description,

Referring to the drawing:

FIGURE 1 is a cross-sectional view, with portions broken awa, of a lift structure made in accordance with this invention. i

FGURE 2 is a perspective View, with portions cut away, of an upper bearing and a hearing supporting gland ring used in the litt of FIGURE l.

' FIGURE 3 is a perspective View, with portions cut away, of a lower bearing ring used in the litt of FlG- URE 1.

FIGURE 4 is a perspective View of a Spanner wrench used in removing the lower bearing ring shown in FIG- URE 3.

Referring to FIGURE l, a lift structure is shown therein including a cylinder member 1t) enclosed at its flower end by a base plate 12. The cylinder may be supported by struts 14 upon a base fixture l5. Normally, the fixture 16 will he located at the bottom of a pit formed in the earth or a lloor. A piston or ram i8, which is cylindrical in shape and concentric with the cylinder lil, is mounted for vertical movement within the cylinder li?. The piston or ram l is provided with a hase plate 2li at its lower end. The top of the piston lt?, comprises a ram bolt ring 22 welded thereto, the bolt ring 22 being provided with a plurality of threaded apertures (not Patented June l, i965 shown) adapted to receive bolts for securing a lift superstructure (not shown) thereto. The bases of the threaded apertures are sealed by a sealing ring 26. To complete the top of the piston, a seal plate 28 is clamped in sealing relation to the bolt ring 22 by a plurality of clamp plates 3d connected to the ring 22.

The litt shown in FIGURE l is of the type known as semi-hydraulic. During installation, the piston 1S and the cylinder l0 are illed nearly full with hydraulic fluid through an aperture, which is normally closed by a till plug 32, located in the plate 2S. To completely lill the cylinder lll around the piston, a bleeder valve 24 is placed in communication with the cylinder 10 through an aperture 34 therein. In operation, air under pressure is supplied to the top of the piston 18 through an air tube 4d projecting longitudinally therethrough which cornmunicates with an air inlet port 42 located in the base fixture lo. The compressed air acts against the top of the piston i3, causing it to rise above the top of the fluid. As the piston rises, vthe fluid therein is for-ced through a port 44 located centrally of the base plate 20 into the cylinder lll. A metering structure 46, located in the port 44, Icontrols the rate of liuid flow passing therethrough, in turn to control the speed of movement of the piston. As shown in FIGURE 1, the metering structure 41 may simply comprise an apertured plate.

The air tube ill) is supported by a generally conical support member Sil secured to the base plate 12 of the cylinder 1d. To yprotect the air tube 40 during shipping, a conical shippingprotector 52 is attached to the bottom surface of the seal plate 28. The member 5?, also serves as a baliie to supply compressed air equal-ly in all directions when the piston is initially raised.

Mounted within the upper portion of the cylinder it) in sealing relation to the piston 1S are an upper bearing structure di? and a packing assembly generally designated 62. The 'packing assembly includes a packing gland ring 66 secu-red, as by a plurality of bolts 68, to a. cylinder bolt ring 7@ welded to the top of the cylinder 10. The bolt ring 76 ymay be integral with a packing support ring 72 which projects downwardly intothe interior of the cylinder 16 and is provided at its vlower end with an inwardly projecting flange or lip portion 74. The packing itself may comprise'a plurality of Chevron-shaped packing members 76 sandwiched between a snap ring 78 supported on the flange portion 74 and the gland ring 65. This type of packing assembly has heen found quite satisfactory in preventing hydraulic iiuid from scoping out around the piston wall. To maintain the surface of the piston i8 clean at all times so as to prevent oil adhered to the surface of the piston from being removed -frorn the piston and to prevent dirt or grit from entering into the cylinder, a wiper ring Sil may be secured within an annular channel title (FIGURE 2) cut in the inner periphery of the gland ring 66 adjacent the surface of the piston i8.

The upper bearing structure 60 may conveniently comprise a strip of bearing material snap t within a second annular channel cut in the inner periphery of the gland ring 66. With the upper bearing structure 60 located above the packing 76, the packing 76 has a long useful life. Were the bearing structure 60 located below the packing, a certain amount of side play of the piston relative to the cylinder 10 would result, thus creating uneven pressure on the packing members 76. However, with the bearing structure 6l) located above the packing, there is little side pressure on the packing member 76. Also, it is well known that a maximum separation between the upper and lower bearings is desirable to achieve the greatest control over the piston movement. This is best obtained by locating the upper bearing adjacent the top of the cylinder above the packing. Since the bearing 60 is snap fit within a channel in the gland ring 66, the cost of the upper bearing is quite small compared to conventional bearings. Also, this structure may be more rapidly assembled than is the case with most prior bearing structures.

The lower bearing structure, designated 82, includes a mounting ring 84 permanently atiixed to the internal wall of the cylinder intermediate its ends. The lower portion of the inner surface of the mounting ring 84 is threaded to accommodate external threads 86 on a lower bearing ring, generally designated 88, and shown best in FIGURE 3. The lower bearing surface is formed on the internal faces of a plurality of circumferentially spaced bearing pads 90, which are substantially equally spaced about the internal circumference of the ring 88. The bearing pads 90 are generally rectangular throughout their length, having generally parallel opposed sides 92 and at bases 94, which are coplanar with the bottom face of the ring 8S. The upper portions of the bearing pads 90, however, are tapered or sloping, as designated at 96, terminating in a pointed top 98. In FIGURE 3, the tapered portions 96 are shown as being straight. However, the sides 92 may depend more or less arcuately outwardly from the tops 98 to the bases 94. The use of spaced bearing pads 90 has several advantages over conventional prior art bearing structures having continuous solid bearing faces. Of course, an important adavntage of such a structure is that foreign matter in the hydraulic iluid will pass between pairs of bearing pads 90 rather than passing along the bearing surfaces thereof. The sloping sides of the upper portions of the pads 90 induce foreign matter to pass between the pads as the piston is being raised. Thus, the life of the bearing surface is prolonged. In addition, air pockets often become trapped beneath solid lower bearing structures hampering the normal operation of the lift. Because the bearing pads 90 are spaced, such air pockets obviously cannot form.

In use, the bearing ring 88 is located, as shown in FIGURE l, in threaded engagement with the mounting ring S4. Normally, the piston or ram 18 cannot move upwardly beyond a limit provided by an enlarged flange 100 formed on the base of the ram 18, which stops against the lower surface of the ring 88. In the past, it has been common to connect lower bearing rings to upper bearing rings by means of a metal sleeve so that removal of the two bearings could be accomplished at the same time. However, it is not feasible to connect the upper and lower bearings where, as here, the upper bearing ring is located above the packing. In accordance with this invention, the lower bearing ring is locked in positon by detent means but may be removed by use of a Spanner wrench, as will be described below.

As shown best in FIGURE 3, a pair of diametrically opposed notches 102 and 104 are cut in the upper portion of the lower bearing ring 88. The lower ends of the notches 102 and 104 are defined by inwardly tapered surfaces designated 106. During assembly, when the ring 88 is threaded into engagement with the ring 84, a detent plunger member 108, which is spring biased by a spring 110 and located within a housing 112 mounted in aligned apertures in the mounting ring 84 and the cylinder 10, enters into one of the notches 102 and 104, preventing further rotation of the bearing ring 88. In practice, the bearing ring 88 will be threaded into engagement with the mounting ring 84 by means of a spanner wrench 114 (FIGURE 4). The Spanner wrench 114 comprises a generally elongate sleeve, having a pair of lugs 116 depending from its lower surface and a pair of handle bars 118 affixed to the upper portion thereof. Only one lug 116 may be seen in FIGURE 4, since the other lug 116 is hidden by the side of the sleeve. The handle bars 118 are diametrically opposed one to the other and each is aligned with one of the lugs 116. When installing a bearing ring 88, the Spanner wrench is slipped over the piston 18 and the lugs 116 insertedpwithin the notches 102 and 104. The bearing ring 3S is then rotated a predetermined number of revolutions. The person installing the bearing ring S8 will be aware that the plunger 108 has begun to enter one of the notches 102, 104 because of a slight click caused by the plunger 108 striking one of the lugs 116. The Spanner wrench 114 is then withdrawn. The packing in the upper bearing ring assembly can then be affixed in position on the top of the cylinder. Removal of the lower bearing is accomplished in the same fashion. Note that each lug 116 has an inwardly tapered bottom face 116er, one of which serves to cam the plunger 108 outwardly into the housing 112 so that the bearing ring 88 may be removed from its engagement with the mounting ring 84. Proper lubrication of the plunger 108 and of the threaded portion of the ring 88 is insured by means of lubricating channels 120, 122 cut in the outer surface of the 88.

Although the presently preferred embodiment of the device has been described, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion and arrangement of parts, the combination thereof and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claims.

Having thus described our invention, we claim:

1. In a vehicle lift having a cylinder and a piston, a bearing structure including a mounting ring connected to said cylinder, a bearing ring having a bearing surface in contact with said piston, said bearing ring being in threaded engagement wtih said mounting ring, detent means supported by said cylinder including a detent member adapted to enter a notch in said bearing ring to lock said bearing ring in a predetermined position, said detent member being removable from said notch.

2. In a lift structure, the combination including: a cylinder, a piston movable within said cylinder, a packing structure including a packing gland ring located adjacent the top of said cylinder and supported thereby, an upper bearing structure adjacent the top of said cylinder in Contact with said piston comprising a strip of bearing material located within a channel in said gland ring, a lower bearing structure intermediate the ends of said cylinder, said lower bearing structure including a mounting ring connected to said cylinder, a bearing ring having a bearing surface in contact with said piston, said bearing ring being in threaded engagement with said mounting ring, detent means supported by said cylinder including a detent member adapted to enter a notch in said bearing ring to lock said bearing ring in a predetermined position, said detent member being removable from said notch, said piston being provided with an enlarged annular flange at its lower end adapted to engage the bottom surface of said lower bearing ring.

3. A bearing ring for a vehicle lift having a cylinder and a piston, said ring having a plurality of cricumferentially spaced bearing pads on the internal face thereof, each of said pads having a bearing surface adapted to contact said piston, and the upper portion of each of said bearing pads having sloping sides.

References Cited bythe Examiner UNITED STATES PATENTS 1,928,465 9/33 Schulz 92--168 2,306,048 12/42 Fast 308--73 2,393,017 l/46 Boyd 308-238 2,854,952 10/58 Wilson 92-168 2,963,175 12/ 60 Thornhill 308-4 RICHARD B. WILKINSON, Primary Examiner.

KARL I. ALBRIGHT, Examiner.

UNITED STATES PATENT OFFICE .l CERTIFICATE 0F CORRECTION Patent No 3 ,186,312 June l 1965 Ion V. KD Hott et al` It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 3, line 28, for "adavntage" vread advantage column 4, line 18, for "lubricating channels 120, 122" read a lubricating channel 122 line 19, after "the" insert Signed and sealed this 3rd day of May 1966.

(SEAL) Attest:

ERNEST W. SWIDER Attesting Ufficer EDWARD J. BRENNER Commissioner of Patents 

1. IN A VEHICLE LIFT HAVING CYLINDER AND A PISTON, A BEARING STRUCTURE INCLUDING A MOUNTING RING CONNECTED TO SAID CYLINDER, A BEARING RING HAVING A BEARING SURFACE IN CONTACT WITH SAID PISTON, AND BEARING RING BEING IN THREADED ENGAGEMENT WITH SAID MOUNTING RING, DETENT MEANS SUPPORTED BY SAID CYLINDER INCLUDING A DETENT MEMBER ADAPTED TO ENTER A NOTCH IN SAID BEARING RING TO LOCK SAID BEARING RING IN A PREDETERMINED POSITION, SAID DETENT MEMBER BEING REMOVABLY FROM SAID NOTCH. 